[gmx-users] mdrun gives different distance restraint potential energies depending on the number of openMP threads

[Szilárd Páll]

Hi,

That should not happen. If the problem it's reproducible, please file
an issue on redmine.gromacs.org.
--
Szilárd


On Tue, Aug 9, 2016 at 11:19 PM, treinz <treinz at 163.com> wrote:
> Hi,
>
>
> I got spuriously large distance restraint potential energy when running mdrun with multiple OpenMP threads and the system adopts a weird configuration sooner or later (depending on the restraint force constant) while the same simulation (same tpr file) runs fine. Here are the Dis. Res. related mdp option I used:
>
>
> disre = simple
> disre-weighting = conservative
> disre-tau = 0
> disre-fc = 1e-5
> nstdisreout = 10000
>
>
> and I tried mdrun using a single MPI rank and giving 1, 2, 4 to -ntomp and only -ntomp = 1 gave sane results. The log file from the 1 OpenMP thread looks like:
>
>
>            Step           Time         Lambda
>               0        0.00000        0.00000
>
>
>    Energies (kJ/mol)
>            Bond          Angle       G96Angle        LJ (SR)   Coulomb (SR)
>     2.16662e+01    0.00000e+00    1.96570e+03    9.15548e+03    0.00000e+00
>      Dis. Rest. D.R.Viol. (nm)      Potential    Kinetic En.   Total Energy
>     5.56697e+04    2.90805e+04    6.68126e+04    1.57240e+04    8.25365e+04
>     Temperature Pressure (bar)
>     2.99970e+02   -6.28303e-07
>
>
> while that from 2 OpenMP threads looks like:
>
>
>            Step           Time         Lambda
>               0        0.00000        0.00000
>
>
>    Energies (kJ/mol)
>            Bond          Angle       G96Angle        LJ (SR)   Coulomb (SR)
>     2.16662e+01    0.00000e+00    1.96571e+03    9.15548e+03    0.00000e+00
>      Dis. Rest. D.R.Viol. (nm)      Potential    Kinetic En.   Total Energy
>     1.96610e+07    4.12632e+05    1.96722e+07    1.57284e+04    1.96879e+07
>     Temperature Pressure (bar)
>     3.00055e+02    5.46943e-06
>
>
> It looks like all the other potential energy terms are the same independent of the number of OpenMP threads except for Dis. Rest.. Can anyone tell me if I'm hitting a bug in GROMACS or if there's something I missed in setting up distance restraint?
>
>
> Thanks,
> Tim
> --
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